Magnet retaining means



Oct. 11, 1966 R. F. EBERLINE 3,278,775

MAGNET RETAINING MEANS Filed 061;. 16, 1965 E- E INVENTOR.

275;; FIZe r/z'zre United States Patent f 3,278,775 MAGNET RETAINING MEANS Richard F. Eberline, Rochester, Mich, assignor to Syncro Corporation, 0xford, Mich., a corporation of Michigan Filed Oct. 16, 1963, Ser. No. 316,675 Claims. (Cl. 310153) This invention relates to magnet retaining means, and more particularly to means for retaining magnets in an engine flywheel for coaction with a magneto ignition coil.

It is an object of the invention to provide a novel and improved magnet retaining means capable of securing two permanent magnets in position within flywheel and at the same time serving as a third magnetic pole.

Other objects, features, and advantages of the present invention will become apparent from the subsequent description, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a partially sectioned fragmentary plan view showing the novel magnet retaining means used in conjunction with an ignition coil;

FIGURE 2 is an enlarged fragmentary view of a portion of the flywheel shown in conjunction with the ignition coil and core;

FIGURE 3 is a cross-sectional view line 33 of FIGURE 2 and showing tions of the parts; and

FIGURE 4 is a side elevational view of the subassembly comprising the magnets, magnet pole pieces and connecting member.

Briefly, the illustrated embodiment of the invention comprises a pair of arcuately shaped permanent magnets such as ceramic magnets having radially disposed poles, pole pieces of magnetizable material secured to concave surfaces of said magnets, and a connecting member of magnetizable material secured to the convex surfaces of the magnets and extending between them, the magnets being space-d circumferentially on a circle concentric with a magneto rotor. The connecting member has a central arcuate portion having a curvature common with those of the pole pieces, radially outwardly extending portions at the opposite ends of the arcuate portions, and arcuate magnet securing portions extending outwardly from said radial portions and secured to the outer magnet surfaces. This entire subassembly may be secured within a flywheel surrounding the magneto coil and core by any of various means, such as by an annular cast ring within the flywheel casing.

Referring more particularly to the drawings, the invention as shown in conjunction with a magneto assembly generally indicated at 11, which is incorporated in an assembly such as an internal combustion engine (not shown) having a vertically disposed crank-shaft 12 to the upper end of which is secured a flywheel generally indicated at 13. Flywheel 13 is shown as comprising an annular casing 14 with a radial wall and an outer flange, and the magnet retaining means is mounted within this casing in a manner described below.

The stator assembly of the magneto comprises a supporting bracket 15 secured to the top of the engine by bolts indicated in dot-dash lines at 16 and a laminated core 17 secured to a pair of parallel branches 18 of frame 16 by fasteners 19. Core 17 is of U-shaped construction, the legs of the core having convex arcuate pole faces 21 and 22 in circumferentially spaced relation. The core is surrounded by a primary winding 23 and a secondary winding 24 in overlapping relation, one end of the primary winding being connected to ground by a wire 25 and the other end to a stationary breaker point 26 on bracket 15 by a wire 27. A movable breaker point 28 is pivotally mounted on bracket 15 and is actuated by a taken along the the relative posi- 3,278,775 Patented Oct. 11, 1966 cam 29 on shaft 12 engageable with a rocking member 30. A high tension lead 31 extends from secondary winding 24.

The magnet retaining means, magnets and pole pieces form a subassembly generally indicated at 32 in FIG- URE 4. The magnets are indicated at 33 and 34, and are permanent magnets such as ceramic magnets having radially oriented poles. In the illustrated example, the inner ends of the magnets are south poles and the outer ends north poles. The magnets have concave arcuate inner surfaces, convex arcuate outer surfaces, and radially extending sides, the arcuate surfaces being concentric with each other, with the configurations of both magnets 33 and 34 being identical. Pole pieces 35 and 36 comprise plates of magnetizable material and are secured to the concave surfaces of the magnets by means such as brazing. The radially outer surfaces of the pole pieces are complementary to the inner surfaces of the magnets, and the inner pole piece surfaces are of arcuate concave shape.

The retaining means comprises a supporting member generally indicated at 37, formed of a bar or strip of magnetizable material such as steel, the strip having a rectangular cross-sectional shape as seen in FIGURE 3. Supporting member 37 comprises a central or pole portion 38, radial portions 39 and 41, and magnet securing portions 42 and 43. Pole portion 38 is of arcuate shape, its curvature corresponding to that of pole pieces 35 and 36. In fact, the cross-sectional shape of member 37 may be the same as that of pole pieces 35 and 36, as seen in FIGURE 3.

Radial portions 39 and 41 extend radially outwardly from the opposite ends of pole portion 38, a distance equal to the depth of magnets 33 and 34. Magnet securing portions 42 and 43 extend circumferentially from portions 39 and 41 in opposite directions. These portions are of arcuate shape, their inwardly facing surfaces being concave and complementary to the outwardly facing surfaces of magnets 33 and 34, so that the magnets may be secured thereto by such means as brazing. The length of portions 42 and 43 is greater than the circumferential extent of magnets 33 and 34, the magnets being secured in spaced relation with radial portions 39 and 41.

With the magnets secured so that like poles, for example, north poles, engage securing portions 42 and 43, the pole portion 38 of supporting member 37 will be of the same polarity. The result will be three circumferentially spaced poles of successively alternate polarity, such as south-north-south. Preferably, the length of pole 38 in a circumferential direction is substantially greater than the length of poles 35 or 36, for example, twice the length, and is also equal to the circumferentially measured distance between stator pole faces 21 and 22. The circumferential length of the spaces indicated at 44 and 45 in FIGURE 4, between pole pieces 35 or 36 and pole 37, is about equal to the circumferentially measured length of pole faces 21 and 22, as seen in FIGURE 2.

subassembly 32 may be secured within flywheel casing 14 by any of various means, and in the illustrated embodiment a nonmagnetizable material such as aluminum is cast in the form of an annular ring 46 within casing 14, with portions of the ring surrounding subassembly 32 and filling spaces 44 and 45, so that the subassembly is securely mounted within the flywheel. In the manufacture of the flywheel, it may be desirable to cast some excess metal radially inwardly of the subassembly and to then turn out this material, so that pole pieces 35 and 36, pole 38 and the material within spaces 44 and 45 will all present a continuous inner surface. The radius of the flywheel will of course be only slightly greater than the radius of curvature of stator pole faces 21 and 22.

In operation, rotation of the flywheel will be accompanied by flux reversals within core 17 as poles 35, 38 and 36 successively pass the stator. These flux reversals Will be accompanied by alternate opening and closing of the primary coil by breaker points 26 and 28, creating the high secondary coil voltage.

While it will be apparent that the preferred embodiment of the invention disclosed is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

. What is claimed is:

1. Magnet retaining means for a flywheel magneto comprising a bar of magnetizable material having a rectangular cross-sectional shape with a central pole portion of arcuate configuration, a pair of radial portions extending radially outwardly from said pole portion toward the convex side thereof, a pair of magnets securing portions extending circumferentially outwardly from the outer ends of said radial portions, said magnet securing portions having a common curvature concentric with the curvature of said pole portion, and a pair of magnets on said magnet securing portions.

2. In a field magnet subassembly, magnet retaining means comprising a bar of magnetizable material having a rectangular cross-sectional shape with a central pole portion of arcuate configuration, a pair of radial portions extending radially outwardly from said pole portion, and a pair of magnet securing portions extending circumferentially outwardly from the outer ends of said radial portions, said magnet securing portions having a comm-on curvature concentric with the curvature of said pole portion, a pair of permanent magnets with radially oriented poles secured to the concave surfaces of said magnet securing portions and extending radially inwardly therefrom, said magnets being circumferentially spaced from said radial portions of the magnet retaining means, and pole pieces of magnetizable material secured to the inner surfaces of said magnets, the inner surfaces of said pole pieces and said pole portion of the magnet retaining means having a common curvature.

3. In a magnetic rotor subassembly, magnet retaining means comprising a bar of rectangular cross-sectional shape fabricated of magnetizable material and having an arcuate central pole portion, a pair of radial portions extending from the ends of said pole portion, and a pair of magnet securing portions extending from the outer ends of said radial portions in opposite directions with a common curvature concentric with the curvature of said pole portion; and a pair of magnets secured to said magnet securing portions and extending radially back toward an arc defining said pole portion, said magnets being spaced from said radial portions.

4. The combination according to claim 3, further provided with a pair of pole pieces secured to the ends of said magnets remote from said magnet securing portions, said pole pieces having a common curvature with said pole portion of the magnet retaining means but being shorter in a circumferential direction than said pole portion.

5. In a magneto construction, a stator core having a pair of circumferentially spaced arcuate pole faces, a flywheel magnet rotor subassembly comprising magnet retaining means, said means being in the form of a bar of rectangular cross-sectional shape and magnetizable material having a central pole portion with a curvature concentric with the curvature of said pole faces and extending circumferentially approximately the distance between said pole faces, radial portions on said bar extending outwardly from the opposite ends of said pole portion, magnet securing portions on said bar extending circumferentially from the outer ends of said radial portions, a pair of permanent magnets having circumferentially measured lengths substantially less than the lengths of said magnet supporting portions and secured thereto, said mag-nets having radially oriented poles and extending back toward the curvature defining said pole portion of the magnet retaining means, and a pair of pole pieces secured to the ends of said magnets remote from said magnet securing portions and having a common curvature with said pole portion, said magnets being spaced from said radial portions of the magnet retaining means a distance approximately equal to the circumferential length of said pole faces, the circumferentially measured lengths of said pole pieces being substantially less than the circumferentially measured length of said retaining means pole portion.

References Cited by the Examiner UNITED STATES PATENTS 2,458,336 1/1949 Brownlee 3l0153 MILTON O. HIRSHFIELD, Primary Examiner.

ORIS L. RADER, Examiner.

A. J. ROSSI, Assistant Examiner. 

1. MAGNET RETAINING MEANS FOR A FLYWHEEL MAGNETO COMPRISING A BAR OF MAGNETIZABLE MATERIAL HAVING A RECTANGULAR CROSS-SECTIONAL SHAPE WITH A CENTRAL POLE PORTION OF ARCUATE CONFIGURATION, A PAIR OF RADIAL PORTIONS EXTENDING RADIALLY OUTWARDLY FROM SAID POLE PORTION TOWARD THE CONVEX SIDE THEREOF, A PAIR OF MAGNETS SECURING PORTIONS EXTENDING CIRCUMFERENTIALLY OUTWARDLY FROM THE OUTER ENDS OF SAID RADIAL PORTIONS, SAID MAGNET SECURING PORTIONS HAVING A COMMON CURVATURE CONCENTRIC WITH THE CURVATURE OF SAID POLE PORTION, AND A PAIR OF MAGNETS ON SAID MAGNET SECURING PORTIONS. 